Scientists hoping a cure is already on the shelf will test at least 2,000 drugs against the frightening SARS virus, although some doubt anything they find will stop the flu-like disease once it gets a foothold.

This search is intended to find an immediate therapy for severe acute respiratory syndrome, or one that could be developed quickly. There is now no proven cure, only treatment that relieves symptoms.

Scientists are almost positive SARS is caused by a newly discovered member of the coronavirus family. Until now, these bugs have been known only to trigger colds or mild diarrhea, so no one has ever tried very hard to find a treatment.

The National Institute of Allergy and Infectious Diseases is gathering up the 30 or so antiviral drugs on the market, about 800 drugs approved for other uses, plus more than 1,000 that are still being developed.

They are being tested at the U.S. Army Medical Research Institute for Infectious Diseases at Fort Detrick, Md.

The lab can test 150 to 200 a drugs week and has started with the most obvious antiviral medicines. But so far, “nothing looks very promising, to be honest,” Army research scientist Peter Jahrling said Wednesday.

At the same time, another team at the University of Virginia hopes soon to enroll SARS victims to test a two-drug strategy already used by some doctors in Hong Kong and Canada, although many are skeptical it will work.

Furthermore, experts expect much more study of the virus. Scientists will look for weaknesses in the bug that might be exploited, as well as a better understanding of how the immune system responds to it. Some experts believe the body’s own defenses are part of the problem.

Health officials in protective gear walk outside Hong Kong's Amoy Garden apartments, where at least 283 cases of severe acute respiratory syndrome, or SARS, have been found. U.S. health officials on Wednesday announced that the Army would test hundreds of existing drugs in hopes of finding a treatment for the illness.

Deciphering the virus’ innermost workings might in the end lead to the most effective drugs. But designing a medicine from scratch is a slow and daunting process, requiring years of testing.

“It’s a fact of life we can’t get around that from the design of a drug on a computer to the point where it can be given to people takes at the very best five years. We hope something will come along in this process that will prove to be effective,” said Dr. Catherine Laughlin, virology chief at the infectious disease institute.

About 50 drug companies took part in a recent conference call with the institute and the Centers for Disease Control and Prevention, and several said they had compounds in development that they would like to try against SARS.

Even if a drug knocks out the virus, it still might not cure SARS. In some infections, much of the damage results from the overwhelming chemical counterattack by the immune system. This cytokine storm, as its called, is intended to kill the virus. But it can have unintended consequences, such as inflammation, leaky blood vessels and even pneumonia, a hallmark of SARS.

“The infection comes on so quickly and you get so sick so fast that it’s unlikely that an antiviral will be rapidly effective,” said Dr. John Zaia, virology chairman at City of Hope National Medical Center in Duarte, Calif. “It may be that the virus has started a process that cannot be stopped.”